Google is desperate not to let Microsoft acquire Yahoo, possibly for the fear that they will face stiffer competition from Microosft as they will have a greater Internet presence. It looks like Yahoo are desperate to avoid being acquired by microsoft. They are talking to a host of other companies.
The issue is that Google can't buyout Yahoo! due to anti-monoploy laws, period. I don't see how they could team up considering they are rivals.
Just found out about this moments ago. Holy crap. Heart attack. Like said before, a merger would no way be possible... but the term "business alliance" gives me the chills.